fix(ai): harden responses replay and failure diagnostics

crates/aether-ai/formats/src/api.rs

@@ -75,6 +75,10 @@ pub use crate::formats::openai::{
         validate_openai_provider_request_contract, OpenAiProviderRequestContractViolation,
         OpenAiProviderRequestFinalization,
     },
+    responses::{
+        openai_responses_synthetic_reasoning_item_id,
+        strip_incompatible_openai_responses_reasoning_items,
+    },
 };
 pub use crate::formats::shared::error_body::{
     build_core_error_body_for_client_format, is_core_error_finalize_kind, LocalCoreSyncErrorKind,

crates/aether-ai/formats/src/formats/conversion/response.rs

@@ -8,7 +8,11 @@ use serde_json::{json, Value};
 
 use crate::formats::{
     context::FormatContext,
-    openai::responses::response::ensure_modern_openai_responses_response_fields, registry,
+    openai::responses::{
+        openai_responses_synthetic_reasoning_item_id,
+        response::ensure_modern_openai_responses_response_fields,
+    },
+    registry,
 };
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
@@ -203,7 +207,7 @@ pub fn build_openai_responses_response_with_content(
         }
         output.push(json!({
             "type": "reasoning",
-            "id": format!("{response_id}_rs_{index}"),
+            "id": openai_responses_synthetic_reasoning_item_id(response_id, index),
             "status": "completed",
             "summary": [{
                 "type": "summary_text",

crates/aether-ai/formats/src/formats/openai/chat/stream.rs

@@ -2,8 +2,11 @@ use std::collections::{BTreeMap, BTreeSet};
 
 use serde_json::{json, Map, Value};
 
-use crate::formats::openai::responses::response::{
-    ensure_modern_openai_responses_response_fields, openai_responses_current_timestamp,
+use crate::formats::openai::responses::{
+    openai_responses_synthetic_reasoning_item_id,
+    response::{
+        ensure_modern_openai_responses_response_fields, openai_responses_current_timestamp,
+    },
 };
 use crate::formats::shared::response::build_generated_tool_call_id;
 use crate::formats::shared::sse::{encode_done_sse, encode_json_sse};
@@ -2223,7 +2226,7 @@ impl OpenAIResponsesClientEmitter {
     fn reasoning_item_id(&self) -> String {
         self.reasoning_item_id
             .clone()
-            .unwrap_or_else(|| format!("{}_rs_0", self.response_id()))
+            .unwrap_or_else(|| openai_responses_synthetic_reasoning_item_id(&self.response_id(), 0))
     }
 
     fn ensure_message_item_id(&mut self) -> String {
@@ -2235,7 +2238,10 @@ impl OpenAIResponsesClientEmitter {
 
     fn ensure_reasoning_item_id(&mut self) -> String {
         if self.reasoning_item_id.is_none() {
-            self.reasoning_item_id = Some(format!("{}_rs_0", self.response_id()));
+            self.reasoning_item_id = Some(openai_responses_synthetic_reasoning_item_id(
+                &self.response_id(),
+                0,
+            ));
         }
         self.reasoning_item_id()
     }
@@ -5216,7 +5222,8 @@ mod tests {
         assert!(sse.contains("event: response.reasoning_summary_text.delta\n"));
         assert!(sse.contains("event: response.reasoning_summary_text.done\n"));
         assert!(sse.contains("event: response.reasoning_summary_part.done\n"));
-        assert!(sse.contains("\"item_id\":\"resp_456_rs_0\""));
+        let reasoning_item_id = openai_responses_synthetic_reasoning_item_id("resp_456", 0);
+        assert!(sse.contains(&format!("\"item_id\":\"{reasoning_item_id}\"")));
         assert!(sse.contains("\"type\":\"reasoning\""));
         assert_eq!(response_sequence_numbers(&sse), (1..=9).collect::<Vec<_>>());
     }

crates/aether-ai/formats/src/formats/openai/request_contract.rs

@@ -85,6 +85,10 @@ pub fn finalize_openai_provider_request_with_codex_model_capabilities(
         body,
         finalization.provider_api_format,
     );
+    super::responses::strip_incompatible_openai_responses_reasoning_items(
+        body,
+        finalization.provider_api_format,
+    );
     crate::enforce_request_body_stream_field(
         body,
         finalization.provider_api_format,
@@ -296,6 +300,42 @@ mod tests {
         }
     }
 
+    #[test]
+    fn finalization_strips_non_replayable_responses_reasoning_history() {
+        let mut body = json!({
+            "model": "gpt-5.4",
+            "input": [
+                {"type": "reasoning", "id": "rs_provider_123", "summary": []},
+                {
+                    "type": "reasoning",
+                    "id": "item_72d3bd8d367d01977ace23f1",
+                    "summary": []
+                },
+                {"type": "message", "role": "user", "content": "continue"}
+            ]
+        });
+
+        finalize_openai_provider_request(
+            &mut body,
+            OpenAiProviderRequestFinalization {
+                source_api_format: "openai:responses",
+                provider_api_format: "openai:responses",
+                provider_type: "openai",
+                provider_model: "gpt-5.4",
+                source_model: "gpt-5.4",
+                body_rules: None,
+                upstream_is_stream: false,
+                require_body_stream_field: false,
+            },
+        )
+        .expect("foreign reasoning history should be sanitized before validation");
+
+        let input = body["input"].as_array().expect("input array");
+        assert_eq!(input.len(), 2);
+        assert_eq!(input[0]["id"], "rs_provider_123");
+        assert_eq!(input[1]["type"], "message");
+    }
+
     #[test]
     fn non_responses_sources_receive_codex_responses_reasoning_defaults() {
         for source_api_format in ["openai:chat", "claude:messages", "gemini:generate_content"] {

crates/aether-ai/formats/src/formats/openai/responses/mod.rs

@@ -7,6 +7,68 @@ pub mod spec;
 pub mod stream;
 
 const TOOL_ERROR_PREFIX: &str = "[tool error]";
+const AETHER_REASONING_ITEM_ID_PREFIX: &str = "rs_aether_";
+
+/// Builds a stable, wire-compatible ID for a reasoning item synthesized by Aether.
+///
+/// The marker lets the outbound request sanitizer distinguish synthetic summaries from
+/// provider-backed reasoning items. Synthetic items without encrypted reasoning state are useful
+/// in client responses, but cannot be replayed as provider-owned reasoning state.
+pub fn openai_responses_synthetic_reasoning_item_id(
+    response_id: &str,
+    output_index: usize,
+) -> String {
+    let seed = format!("{response_id}:{output_index}");
+    format!(
+        "{AETHER_REASONING_ITEM_ID_PREFIX}{}",
+        uuid::Uuid::new_v5(&uuid::Uuid::NAMESPACE_OID, seed.as_bytes()).simple()
+    )
+}
+
+/// Removes reasoning history items that cannot be replayed against an OpenAI Responses backend.
+///
+/// Reasoning IDs are opaque provider references and must never be repaired by changing their
+/// prefix. Foreign IDs (for example `item_...`) are therefore removed. Aether-synthesized
+/// reasoning summaries are also removed unless they carry encrypted reasoning state that can be
+/// replayed statelessly.
+pub fn strip_incompatible_openai_responses_reasoning_items(
+    body: &mut Value,
+    provider_api_format: &str,
+) -> usize {
+    if !aether_ai_formats::is_openai_responses_family_format(provider_api_format) {
+        return 0;
+    }
+    let Some(items) = body.get_mut("input").and_then(Value::as_array_mut) else {
+        return 0;
+    };
+    let original_len = items.len();
+    items.retain(openai_responses_reasoning_item_is_replayable);
+    original_len.saturating_sub(items.len())
+}
+
+fn openai_responses_reasoning_item_is_replayable(item: &Value) -> bool {
+    let Some(object) = item.as_object() else {
+        return true;
+    };
+    if object.get("type").and_then(Value::as_str) != Some("reasoning") {
+        return true;
+    }
+    let Some(id) = object
+        .get("id")
+        .and_then(Value::as_str)
+        .map(str::trim)
+        .filter(|id| id.starts_with("rs"))
+    else {
+        return false;
+    };
+    if !id.starts_with(AETHER_REASONING_ITEM_ID_PREFIX) {
+        return true;
+    }
+    object
+        .get("encrypted_content")
+        .and_then(Value::as_str)
+        .is_some_and(|encrypted_content| !encrypted_content.trim().is_empty())
+}
 
 /// Semantic operation carried by an OpenAI Responses request that asks the
 /// service to compact a thread. The request still uses the Responses wire
@@ -56,7 +118,10 @@ fn encode_tool_result_error(output: Value, is_error: bool) -> Value {
 mod tests {
     use serde_json::json;
 
-    use super::{openai_responses_request_operation, OPENAI_RESPONSES_OPERATION_COMPACT};
+    use super::{
+        openai_responses_request_operation, openai_responses_synthetic_reasoning_item_id,
+        strip_incompatible_openai_responses_reasoning_items, OPENAI_RESPONSES_OPERATION_COMPACT,
+    };
 
     #[test]
     fn resolves_compaction_trigger_as_compact_operation_on_responses_transport() {
@@ -88,4 +153,60 @@ mod tests {
             Some(OPENAI_RESPONSES_OPERATION_COMPACT)
         );
     }
+
+    #[test]
+    fn synthetic_reasoning_item_ids_are_stable_and_wire_compatible() {
+        let first = openai_responses_synthetic_reasoning_item_id("resp_123", 0);
+        let second = openai_responses_synthetic_reasoning_item_id("resp_123", 0);
+        let other = openai_responses_synthetic_reasoning_item_id("resp_123", 1);
+
+        assert!(first.starts_with("rs_aether_"));
+        assert_eq!(first, second);
+        assert_ne!(first, other);
+    }
+
+    #[test]
+    fn strips_foreign_and_non_replayable_synthetic_reasoning_items() {
+        let portable_synthetic = openai_responses_synthetic_reasoning_item_id("resp_123", 1);
+        let local_synthetic = openai_responses_synthetic_reasoning_item_id("resp_123", 2);
+        let mut body = json!({
+            "input": [
+                {"type": "reasoning", "id": "rs_provider_123", "summary": []},
+                {"type": "reasoning", "id": "item_72d3bd8d367d01977ace23f1", "summary": []},
+                {"type": "reasoning", "id": "resp_123_rs_0", "summary": []},
+                {"type": "reasoning", "summary": []},
+                {
+                    "type": "reasoning",
+                    "id": portable_synthetic,
+                    "summary": [],
+                    "encrypted_content": "opaque"
+                },
+                {"type": "reasoning", "id": local_synthetic, "summary": []},
+                {"type": "message", "id": "item_message_123", "role": "user", "content": "hi"}
+            ]
+        });
+
+        assert_eq!(
+            strip_incompatible_openai_responses_reasoning_items(&mut body, "openai:responses"),
+            4
+        );
+        let input = body["input"].as_array().expect("input array");
+        assert_eq!(input.len(), 3);
+        assert_eq!(input[0]["id"], "rs_provider_123");
+        assert_eq!(input[1]["encrypted_content"], "opaque");
+        assert_eq!(input[2]["id"], "item_message_123");
+    }
+
+    #[test]
+    fn reasoning_item_sanitizer_is_scoped_to_responses_targets() {
+        let mut body = json!({
+            "input": [{"type": "reasoning", "id": "item_foreign", "summary": []}]
+        });
+
+        assert_eq!(
+            strip_incompatible_openai_responses_reasoning_items(&mut body, "openai:chat"),
+            0
+        );
+        assert_eq!(body["input"].as_array().map(Vec::len), Some(1));
+    }
 }

crates/aether-ai/formats/src/formats/openai/responses/response.rs

@@ -5,7 +5,7 @@ use std::{
 
 use serde_json::{json, Map, Value};
 
-use super::encode_tool_result_error;
+use super::{encode_tool_result_error, openai_responses_synthetic_reasoning_item_id};
 
 use crate::{
     formats::context::FormatContext,
@@ -198,7 +198,10 @@ pub fn to_raw(canonical: &CanonicalResponse, report_context: &Value, compact: bo
                 item.insert("type".to_string(), Value::String("reasoning".to_string()));
                 item.insert(
                     "id".to_string(),
-                    Value::String(format!("{}_rs_{}", response_id, output.len())),
+                    Value::String(openai_responses_synthetic_reasoning_item_id(
+                        &response_id,
+                        output.len(),
+                    )),
                 );
                 item.insert("status".to_string(), Value::String("completed".to_string()));
                 if let Some(encrypted_content) = encrypted_content {
@@ -712,6 +715,9 @@ mod tests {
 
         let rebuilt = to_raw(&canonical, &json!({}), false);
         assert_eq!(rebuilt["output"][0]["type"], "reasoning");
+        assert!(rebuilt["output"][0]["id"]
+            .as_str()
+            .is_some_and(|id| id.starts_with("rs")));
         assert_eq!(
             rebuilt["output"][0]["encrypted_content"],
             json!("openai-opaque")

crates/aether-ai/formats/src/formats/shared/standard_matrix.rs

@@ -150,6 +150,10 @@ pub fn build_standard_request_body_with_model_directives_and_request_headers(
         &mut provider_request_body,
         provider_api_format,
     );
+    crate::formats::openai::responses::strip_incompatible_openai_responses_reasoning_items(
+        &mut provider_request_body,
+        provider_api_format,
+    );
     strip_openai_responses_input_content_cache_control(
         &mut provider_request_body,
         provider_api_format,

crates/aether-ai/formats/src/formats/shared/standard_normalize.rs

@@ -297,6 +297,10 @@ pub fn build_local_openai_responses_request_body_with_model_directives(
         require_streaming,
         require_body_stream_field,
     );
+    crate::formats::openai::responses::strip_incompatible_openai_responses_reasoning_items(
+        &mut provider_request_body,
+        "openai:responses",
+    );
     Some(provider_request_body)
 }
 

crates/aether-ai/formats/src/formats/shared/sync_products.rs

@@ -7,6 +7,7 @@ use aether_ai_formats::formats::conversion::response::{
     convert_openai_chat_response_to_openai_responses,
     convert_openai_responses_response_to_openai_chat,
 };
+use aether_ai_formats::formats::openai::responses::openai_responses_synthetic_reasoning_item_id;
 use aether_ai_formats::formats::openai::responses::response::ensure_modern_openai_responses_response_fields;
 use aether_ai_formats::formats::registry::{convert_response, FormatContext, FormatError};
 use aether_ai_formats::{
@@ -3185,8 +3186,9 @@ fn materialize_openai_responses_reasoning_item(
     let mut item = state.item;
     item.entry("type".to_string())
         .or_insert_with(|| Value::String("reasoning".to_string()));
-    item.entry("id".to_string())
-        .or_insert_with(|| Value::String(format!("{response_id}_rs_0")));
+    item.entry("id".to_string()).or_insert_with(|| {
+        Value::String(openai_responses_synthetic_reasoning_item_id(response_id, 0))
+    });
     item.entry("status".to_string())
         .or_insert_with(|| Value::String("completed".to_string()));
     if !state.summary_text.is_empty() {

crates/aether-ai/formats/src/lib.rs

@@ -52,7 +52,8 @@ pub use formats::openai::responses::request::{
     validate_openai_responses_request_contract, OpenAiResponsesRequestContractViolation,
 };
 pub use formats::openai::responses::{
-    openai_responses_request_operation, OPENAI_RESPONSES_OPERATION_COMPACT,
+    openai_responses_request_operation, openai_responses_synthetic_reasoning_item_id,
+    strip_incompatible_openai_responses_reasoning_items, OPENAI_RESPONSES_OPERATION_COMPACT,
 };
 pub use formats::registry::{
     build_stream_transcoder, convert_request, convert_request_pure,